.big{ 
    background: url(../../assets/sunjunpchuazhoutu.jpeg) center center  no-repeat ;
    background-size: cover;
    width: 100vw;
    height: 100vh;
    
    
   .box{
        position: fixed;
         top:30%;
         left: 15%;
        width: 70vw;



    
    
  
}
}